The present invention relates to an improved apparatus for roll finishing bevel gears, and more particularly, the invention provides for an adjusting means which offers extreme rigidity and precision for adjusting the root angle formed on a workpiece.
It is known in the art to roll finish bevel gear workpieces by applying a relatively high force between a die and a workpiece which are brought into meshing engagement. By feeding the die and the workpiece relative to each other it is possible to displace up to several thousandths of an inch of material on previously formed tooth profiles of the workpiece, and this serves to finish the tooth profiles to a final dimension and surface condition. Machines for carrying out this type of basic operation were disclosed as early as 1928 in Gleason et al U.S. Pat. No. 1,669,818 and have been disclosed in more recent years in U.S. Pat. Nos. 3,604,235 and 3,605,467, for example. As noted in the just-mentioned patent disclosures, apparatus for roll forming may typically include a first spindle means for carrying a gear member and a second spindle means for carrying a pinion member for meshing with the gear member during the rolling operation. Either the gear member or the pinion member may be a die for imparting final tooth profiles on a workpiece, and the other of the gear member or the pinion member comprises the workpiece itself.
Roll forming equipment requires relatively strong and rigid machine components because of the very high force loads required to displace material on a cold workpiece by the forceful engagement of a die with the workpiece. Thus, recent designs for such equipment have tended to contain and support the separate spindles of the machine so as to establish a rigid and fixed angular relationship between the pinion member and the gear member. Typically, this relationship has provided for a right angular disposition of the axes of rotation of the two members, and one axis may be offset from the other when a hypoid pinion or gear is being finished. In addition to fixed angular relationships, the early U.S. Pat. No. 1,669,818 provided for an adjustment of one spindle axis relative to the other for purposes of adjusting the root angle (also referred to as pressure angle) relationship between a meshing pinion and gear. However, the type of adjustment shown in U.S. No. 1,669,818 was not applied to a machine of the type contemplated herein in which both the die axis and the workpiece axis are movable about pivot points for effecting (a) initial engagement and final disengagement of the die and the workpiece and (b) relative feeding of the die and the workpiece during the rolling operation to obtain full depth of roll. In contrast, the root angle adjustment means of the present invention can be used with apparatus having such pivotal feed motions for its separate spindle axes, and makes provision for such pivotal feed motions without loss of a root angle setting. In addition, the root angle adjusting means of the present invention is positioned in close proximity to the working end of a spindle, and this establishes a fixed and precise stop limit which is not lost through bending moments of the spindle.
In accordance with a preferred embodiment of the present invention, a machine frame is designed to support the loads of a first spindle means carrying a gear member and a second spindle means carrying a pinion member so that the pinion and gear members can be brought into meshing engagement with one another for roll forming tooth profiles on whichever one of the members comprises a workpiece. The first spindle means is mounted for movement about a pivot axis which intersects the axis of rotation of the second spindle means to thereby provide for a pivotal feeding motion of the gear member relative to the pinion member. The second spindle means is likewise mounted for pivotal movement about an axis, and its movement functions to engage and disengage the pinion and gear at the beginning and end of each rolling operation for loading and unloading purposes. In the illustrated embodiment, the root angle adjusting means is operatively associated with the second spindle means, and thus, the adjusting means of this invention is designed and constructed to accommodate the pivotal motions of the second spindle means in its movements for engaging and disengaging a meshing pinion and gear.
In accordance with a specific embodiment of the invention the adjusting means includes a movable wedge-shaped member carried by the machine frame for establishing a stop surface against which a movable portion of the second spindle means (or its associated mounting means) can be moved when the second spindle means is pivoted to bring a pinion member into meshing engagement with a gear member. The adjusting means is positioned in close proximity to the working end of one of the movable spindles of the machines so that a precisely defined position for the stop surface can be maintained during a rolling operation. In addition, the invention provides for means for displacing the adjusting means completely out of its operative position to thereby remove the stop surface to provide clearance for gross movements of the second spindle means about its pivot axis. The displacing means is arranged to move the wedge-shaped member transversely from its adjusted position so that it can be returned to its operative position without loss of precision in whatever root angle setting has been set up for a particular job. Thus, gross movements of the second spindle means, as required for loading and unloading the apparatus, can be accomplished without disrupting a precision setting of the root angle relationship between a pinion and a gear.
These and other features and advantages of the root angle adjusting means of the present invention will become apparent in the more detailed discussion which follows, and in that discussion reference will be made to the accompanying drawings as briefly described below: